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Abstract:

A deflection component for a luminaire is hollow and consists of two
sections, of which a first section is parallel to the axis and a second
section in contrast runs obliquely outwards.

Claims:

1. A deflection component for use in a luminaire, which defines an axis,
together with a high-pressure discharge lamp, characterized in that the
deflection component is hollow and comprises two sections, the first
section being a hollow-cylindrical part, which is aligned axially
parallel, while a second section, adjoining said first section, is
inclined outwards at an angle with respect to the axis.

2. The deflection component as claimed in claim 1, characterized in that
it is manufactured from sprung sheet metal.

3. The deflection component as claimed in claim 2, characterized in that
at least one tongue is stamped out in the first section, which tongue
acts as a holding means.

4. A luminaire, which defines a longitudinal axis, having a high-pressure
discharge lamp, in which a discharge vessel is the only bulb, the
discharge vessel being aligned axially and having two seals, the
luminaire having a housing with a concave, rotationally symmetrical
reflector, and being equipped with an apex opening at the end of the
reflector, a holding apparatus for the first seal of the discharge vessel
being fitted in the region of said reflector, the luminaire also having a
deflection component in accordance with claim 1.

5. The luminaire as claimed in claim 4, characterized in that the
deflection component is fixed directly on the first seal

6. The luminaire as claimed in claim 4, characterized in that the
deflection component is a separate part, which is connected to a housing
part, in particular to the holding apparatus.

7. The luminaire as claimed in claim 4, characterized in that the
luminaire has an additional cooling apparatus in the region of the second
seal.

8. The luminaire as claimed in claim 7, characterized in that the cooling
apparatus comprises at least one cooling plate, which is arranged
transversely with respect to the axis of the luminaire.

9. A luminaire, which defines a longitudinal axis, having a high-pressure
discharge lamp, in which a discharge vessel is the only bulb, the
discharge vessel being aligned axially and having two seals, the
luminaire having a housing with a concave, rotationally symmetrical
reflector, and being equipped with an apex opening at the end of the
reflector, a holding apparatus for the first seal of the discharge vessel
being fitted in the region of said reflector, the luminaire also having a
deflection component in accordance with claim 2.

10. A luminaire, which defines a longitudinal axis, having a high-pressure
discharge lamp, in which a discharge vessel is the only bulb, the
discharge vessel being aligned axially and having two seals, the
luminaire having a housing with a concave, rotationally symmetrical
reflector, and being equipped with an apex opening at the end of the
reflector, a holding apparatus for the first seal of the discharge vessel
being fitted in the region of said reflector, the luminaire also having a
deflection component in accordance with claim 3.

Description:

TECHNICAL FIELD

[0001]The invention is based on a deflection component for a luminaire in
accordance with the precharacterizing clause of claim 1. In particular,
the deflection component here is one for a luminaire having metal-halide
lamps with a pinch seal at two ends, primarily with a high power rating.

PRIOR ART

[0002]Such lamps are known in principle from EP 391 283 and EP 451 647.
They are suitable for horizontal and vertical arrangement in a reflector.

[0003]A generic lamp is known from DE-A 38 29 156 which is installed
horizontally in an associated luminaire.

DESCRIPTION OF THE INVENTION

[0004]The object of the present invention is to provide a deflection
component in accordance with the precharacterizing clause of claim 1
which extends the life of the lamp in the luminaire even in the case of
an unfavorable operating position.

[0005]This object is achieved by the characterizing features of claim 1.
Particularly advantageous configurations can be found in the dependent
claims.

[0006]A further object is that of providing a luminaire which comprises a
deflection component and a reflector, the luminaire efficiency being as
high as possible and at the same time the life being very long.

[0007]This object is achieved by the characterizing features of claim 3.
Particularly advantageous configurations can be found in the dependent
claims.

[0008]Specifically, the invention proposes a deflection component which is
particularly suitable, in interaction with a high-pressure discharge lamp
which has a metal halide filling, for vertical operation in a luminaire.
This high-pressure discharge lamp has, as its features, an elongated
discharge vessel, which defines an axial axis of symmetry and is sealed
at two ends by seals, for example pinch seals or fuse seals, and
surrounds a discharge volume, two electrodes opposing one another on the
axis, and which contains an ionizable filling consisting of mercury,
noble gas and metal halides, as well as power supply lines, which are
connected to the electrodes via foils and which emerge at the ends of the
discharge vessel. Typically, the lamp consumes a power of at least 600 W.

[0009]When they are installed in a luminaire, such lamps often have
problems with their life as a result of uneven thermal loading. This
applies in particular also in the case of an alignment close to the
vertical, whereby the lamp is deflected from the vertical by no more than
45°.

[0010]Typically, until now it has therefore been attempted to provide
forced cooling of the luminaire by means of a fan. The fan is fitted in
the vicinity of the base. Its air flow reaches the lamp through slits in
the housing. In terms of operation, it would be desirable for the end of
the lamp which accommodates the cold spot to be heated, while the
opposite, warmer end in the region of the second seal is cooled, with the
result that best-possible isothermy is produced. However, the fan has
precisely the opposite effect. The air principally flows past the first,
lower seal and cools it instead of warming it. The air flow passes along
the lamp and finally reaches the second, upper seal and cools it, but
much less effectively than the first seal.

[0011]According to the invention, a deflection component is therefore
provided which has a first section which is matched to the seal of the
lamp and surrounds this first seal tightly, and a second section which
protrudes at an angle outwards therefrom and is selected such that it
firstly keeps the air flow away from the lower half of the discharge
volume and deflects it only towards the upper half. At the same time,
however, the length of the second section should be selected to be so
short that it cannot result in shadowing of the discharge arc. The
discharge vessel is the only bulb of the lamp and typically has an
axially asymmetrical reflecting coating at a first end of the discharge
volume for the axial installation in a reflector in a limited region,
which includes the coldest point. Preferably, the coating is a metallic
or nonmetallic layer, in particular consisting of zirconium oxide.

[0012]Typically, the coating extends so as to face the discharge as far as
the tip of the electrode. In another embodiment, it is sufficient if it
extends as far as the beginning of the head or merely on the seal. The
head is often a ball or coil.

[0013]Typically, the coating extends facing away from the discharge
towards the foil. The design of the coating finally depends on the
details such as filling composition, desired color temperature and
thermal loading in the luminaire, however.

[0014]In order to improve the thermal economy, some of the two pinch seals
may be given a matt finish, as is known per se. In this case, the
matt-finishing is preferably a coating which has been roughened by means
of sandblasting or etching.

[0015]In particular metal halides from the group of elements consisting of
Na, Tl, Cs and rare earth metals are suitable as the component of the
filling since with them it is possible to easily set a color temperature
of at least 4000 K.

[0016]Preferably, the lamp is operated in a luminaire in a vertical
operating position, the coldest point (T) being positioned at the lowest
point.

[0017]The high-pressure discharge lamp is designed to be particularly
compact by virtue of the fact that the discharge vessel (2) is the only
bulb.

[0018]The high-pressure discharge lamp may advantageously have electrodes
with a shaft and head, in the case of which the shafts have a diameter of
at most 1 mm.

[0019]A further aspect of the invention is directed at a luminaire having
the high-pressure discharge lamp outlined at the outset and the
deflection component. In this case, the luminaire has a concave,
rotationally symmetrical reflector having an optical axis, which
corresponds with the lamp axis, an apex, which is open in the region
where the optical axis intersects the reflector, and contains a holding
apparatus for the first end of the discharge vessel, the luminaire having
the deflection component which acts as a cooling apparatus for the lamp
in the region of this first end.

[0020]In this case, an advantageous embodiment is that the cooling
apparatus is a cooling plate which is arranged substantially axially
parallel, that end of the cooling plate which faces the discharge
protruding outwards at an angle approximately at the height of the end of
the discharge vessel. Particularly suitable is an angle of
45±20° and a length of the second section which is dimensioned
such that the upper edge of the deflection component ends approximately
at the height of the electrode head.

[0021]In particular, in addition a further deflection component can be
associated with the second power supply line. Advantageously, this second
deflection component does not rest on the second pinch seal. It is more
effective if it at least has a gap of 5 mm from the second seal.
Advantageously, an efficient effect is realized with the second
deflection component by virtue of the fact that it comprises at least one
metal sheet, which is arranged transversely with respect to the axis of
the reflector. This high degree of efficiency is associated with the fact
that the diameter of the reflector in the region of the second deflection
component is already much wider than in the vicinity of the apex.

[0022]Advantageously, the second power supply line is connected to a solid
return line.

[0023]In particular, the luminaire is designed for general lighting
purposes. Correspondingly, it is designed for a life of at least 2500
hours. In this case, a particularly high degree of compactness is in
particular achieved by virtue of the fact that the two electrical
connections are arranged in the region of the apex.

[0024]Particularly advantageously, the return line is guided closely past
the discharge vessel back to the apex in order to keep shadowing to a
minimum. A particularly compact luminaire is realized by the return line
ending in the holding apparatus.

[0025]The lamp according to the invention achieves a life of at least 2500
hours even during vertical operation in a compact luminaire, and, given
an optimum design of the luminaire with suitable cooling apparatuses, the
life is at least 4500 hours. Vertical operation allows a particularly
high luminous efficiency.

[0026]For applications in rooms or at dusk, the light color neutral white
and, for very stringent requirements as regards the color rendition,
neutral white deluxe NDL is very suitable with a color temperature of
approximately 4100 to 4400 K and an Ra of at least 84.

[0027]The lamp according to the invention is also suitable for indirect
lighting, for example with reflector spotlight systems in which a high
luminous flux is required.

[0028]It is suitable for a novel modular luminaire concept in which a
given lamp can be matched to different specially designed luminaires by
the coating on the lamp being optimized and by possibly corresponding
deflection components being provided in the luminaire. The operating
position, the light color and power of the lamp can therefore be matched
ideally to the boundary conditions of the luminaire.

[0029]The cooling apparatuses are designed such that they allow a maximum
temperature drop between the upper and lower foil, in particular their
ends remote from the discharge, of 150° C. during operation.
Furthermore, the cooling apparatuses are designed such that they
guarantee a maximum temperature of the lamp during operation of at most
390° C.

[0030]Light-active metal halide fillings often contain sodium as a
constituent. High luminous efficiencies and the desired color components
can therefore be achieved. On the other hand, a high sodium content
results in increased corrosion of the discharge vessel, although it is
usually produced from quartz glass. The content of Na is therefore often
relatively low and in particular is supplemented or replaced entirely or
partially by thallium, cesium or other rare earth metals such as Dy, Hm
or Tm.

[0031]Preferably, in the case of lower-wattage lamps, in particular 600 to
1600 W, the ends of the discharge vessel are coated up to the tip of the
electrode; this is primarily the case for neutral white fillings with a
color temperature of from 4000 to 4800 K. Overall, the temperature of the
cold spot, but also the foil end temperature and the wall loading is
thereby increased, with the result that they reach optimum values.

[0032]Preferably, in the case of higher-wattage lamps, in particular 1700
to 2000 W or more, fillings with a low content of Na or no content of Na
at all are preferably used. Since this lamp is subjected to markedly
greater thermal loads, matt-finishing of the pinch seals is in this case
particularly recommendable. This makes it possible to limit the
temperature of the lamp to a maximum of 350° C. even in a narrow
luminaire. This applies both to a horizontal and a vertical operating
position.

[0033]Particularly critical is the temperature at the foil end. The
matt-finishing should therefore in each case include the region of the
outer foil end. Advantageously, it extends up to the end of the pinch
seal. On the inside, towards the discharge, it can extend at least to the
center of the foil, under certain circumstances also markedly beyond
this, for example as far as the inner end of the foil.

[0034]Typical gaps between the electrode tips are 25 to 35 mm for
particularly compact luminaires, but also gaps of up to 100 mm or more
are possible.

[0035]In such compact luminaires, the lamp and the reflector form a single
thermal system, which needs to meet the requirements of the lamp, in
particular a maximum temperature of 390° C. For this purpose, at
least one thermal cooling apparatus is fitted in the luminaire in such a
way that it brings about as little shadowing as possible. This requires
an arrangement of the cooling apparatuses which is as close to the axis
as possible.

[0036]An efficient means for thermal influencing is an open apex of the
reflector, so that cool air can enter the reflector from below. This air
can then flow past the lower pinch seal. In particular, the cooling
apparatus is realized by a fan or by openings in the apex with covering.
Different admittance values can therefore be set, depending on the
specific configuration of the reflector.

[0037]An increase in the admittance value is in this case achieved by a
deflection component, which is fitted directly to the lower first pinch
seal. It comprises spring sheet metal and can be clipped or pushed onto
the pinch seal and provided with a tongue acting as a barb. It can then
be fitted onto the lamp in a simple manner before said lamp is installed
in the luminaire. This is, for example, a cooling plate, which runs
substantially axially parallel and ends at the height of the pinch seal.
The cooling effect is particularly effective owing to the fact that the
second section of the cooling plate protrudes from the axis at the height
of the pinch seal.

[0038]Alternatively, the deflection component may be a separate part of
the luminaire which is equipped with a holding apparatus and surrounds
the first seal at a slight distance.

[0039]Additional cooling can be provided at the second end of the
discharge vessel. However, it is surprisingly not so much the pinch seal
which is at risk here, but that end of the pinch seal from which the
power supply line emerges towards the outside. Here, undesirable cracks
or capillaries are formed which may lead to a lack of sealtightness. In
order to avoid this, the additional cooling is provided above the second
pinch seal, for example at a distance of approximately 5 to 15 mm.
Particularly advantageous is a cooling plate with deflecting ribs
positioned transversely with respect to the axis.

[0040]The heat dissipation is advantageously further improved by virtue of
the fact that the return line is designed to be solid, with the result
that it can itself act as a holder. A rod with a diameter of at least 5
mm is suitable for this purpose. It should consist in particular of
corrosion-resistant molybdenum.

FIGURES

[0041]The invention will be explained in more detail below with reference
to a plurality of exemplary embodiments. In the figures:

[0042]FIG. 1 shows a metal-halide lamp in a side view;

[0043]FIG. 2 shows an exemplary embodiment of a deflection component;

[0044]FIG. 3 shows an exemplary embodiment of a luminaire in a side view;

[0045]FIG. 4 shows a further exemplary embodiment of a luminaire in a side
view.

DESCRIPTION OF THE DRAWINGS

[0046]FIG. 1 illustrates schematically a 2000 W high-pressure discharge
lamp 1 without an outer bulb having a length of approximately 190 mm, as
is described in more detail, for example, in U.S. Pat. No. 5,142,195. It
is intended for use in reflectors, it being arranged axially with respect
to the reflector axis.

[0047]The discharge vessel 2 consisting of quartz glass defines a
longitudinal axis X and is in the form of a barrel body, whose generatrix
is the arc of a circle. The discharge volume is approximately 20
cm3. The rod-shaped tungsten electrodes 4 with a coil pushed on as
the head are axially aligned in pinch seals 3 at both ends of the
discharge vessel. The electrodes 4 are fixed to foils 8 in each case in
the pinch seal 3a, 3b, to which external power supply lines 7 are
attached. A ceramic base 5 is fixed with cement 6 to that end 20 of the
pinch seal 3 which is remote from the discharge. The discharge vessel 2
contains a filling consisting of a noble gas, mercury and metal halides.
The first end of the discharge volume is provided with a heat
accumulation dome 9 consisting of zirconium oxide.

[0048]The dome 9 extends around the pinch-seal edge 21, precisely in such
a way that its end 10 facing the discharge ends with the tip of the
electrode. The head of the electrode in this case also comprises a coil
pushed onto the tip. That end 13 of the coating which is remote from the
discharge has a gap of approximately 2 mm from the pinch-seal edge.

[0049]The lower first pinch seal 3a is additionally provided with a
matt-finish 11, which extends from the outer end of the pinch seal 20 as
far as beyond the center of the foil as far as approximately 70% of the
foil length. The inner end of the matt finish is denoted by 14.

[0050]The upper second pinch seal 3b is also provided with a matt-finish
12. However, this extends from the outer end of the pinch seal 20 as far
as beyond the inner end of the foil as far as close to the pinch-seal
edge. The inner end of the matt finish is denoted by 19.

[0051]In this exemplary embodiment, the light color daylight is realized
by the filling. In this case, the upper pinch seal is limited to a
maximum temperature of 390° C. by the matt finish alone. The lower
pinch seal has a shorter matt finish (axial length is 35 mm) and the
coating 9. Together, these increase the temperature of the cold spot,
which is located in the vicinity of the lower pinch-seal edge 21, as far
as possible. The matt finish and the coating together fix the temperature
distribution at the shaft 23 of the electrode. An optimum temperature
distribution which is as even as possible delays the corrosion of the
shaft by means of halogens, which are a constituent of the filling. In
this case, it has proven advantageous to use iodine on its own or both
bromine and iodine as halogens, wherein a ratio of bromine to iodine of
at most 1.45 is favorable. In particular, this ratio is approximately 0.6
to 1.2. As a result, erosion on the shaft is minimized and nevertheless
good maintenance of the luminous flux (85% after an operating time of
2500 hours) is achieved. The uniform temperature distribution makes it
possible to use thinner pins as the shaft (0.5 to 1 mm in diameter),
which can be embedded more tightly in the quartz glass during
pinch-sealing and reduce the volume of the capillaries. Such a thin shaft
needs to be compatible with the design of the halogen cycle process, in
particular by careful selection of the bromine to iodine ratio as
explained above. Such thin shafts also restrict the dissipation of heat,
with the result that an additional accumulation of heat arises at this
point which prevents the occurrence of metal halide deposits. As a
result, the reflector coating is reduced to a small axial length, which
reduces shadowing. The maximum extent is approximately as far as the
electrode tip, but it preferably reaches at most to the beginning of the
head of the electrode. Under certain circumstances, the coating can even
be dispensed with entirely if the shaft can be dimensioned to be
sufficiently thin. A relatively narrow coating also reduces the wall
loading brought about thereby. Desirable is a value for the wall loading
of at least 50 and at most 70 W/cm2.

[0052]FIG. 2 shows an exemplary embodiment of the deflection component 15.
It is hollow on the inside. It comprises an approximately square first
section 16, which runs axially parallel to the axis of the lamp, a second
section 17, which is widened in the form of a funnel and reaches
approximately as far as the height of the electrode head, resting on the
upper end of said first section 16. The angle of the inclination is
approximately 45°. Tongues 18 (only one is visible) are stamped
out on the two broad sides of the first section, which tongues 18 are
anchored on elevations on the pinch seal of the lamp.

[0053]FIG. 3 shows a side view of a luminaire, which substantially
comprises the lamp 1 and the reflector 25 as well as a base part 24.
Further housing parts which are not essential have been omitted. The lamp
1 is held in the apex of the reflector by a holding apparatus 33, which
surrounds the lower end of the first pinch seal and rests on the base
part 24. In addition, the holding apparatus accommodates the return line
27, which holds the upper pinch seal via a collar 26. The return line 27
is connected to the upper outer power supply line 7, which is in the form
of a braided wire. The base part 24 also has contacts 32.

[0054]In addition, the luminaire comprises a cooling apparatus at the
lower end by openings 34 in the base allowing the air flow originating
from a fan 31 to circulate, which air flow is deflected by the deflection
part 15. Further slots 35 allow the air flow to emerge again at the
base-side end. The deflection part 15 is fixed on the lower pinch seal
3a, in particular by means of the tongues 18 (not visible).

[0055]In a particularly preferred embodiment (FIG. 4), firstly the power
supply line 7 is so solid that it bears a circular collar 30, which acts
as an additional cooling plate. In this case, the collar acts as an
active heat dissipation means, which is fitted to the power supply line 7
approximately 10 mm behind the end of the upper second pinch seal. One
alternative is a cooling plate arrangement comprising three plates, which
are positioned one behind the other transversely with respect to the axis
of the reflector.

[0056]In this case it is not the deflection component 15' which is fixed
to the pinch seal 3a, but a separate part, which is fixed in the
receptacle 22, and is slightly spaced apart from the pinch seal 3a. In
general, the deflection component is manufactured from spring sheet
metal.